Gaseous electric discharge lamp device



Nov. 12, 1935. 5. mm: ET AL 2,020,724

GASEOUS ELECTRIC DISCHARGE WP DEVICE Filed Feb. 5, 1934 s 1 I a 2 2, 6

TTO NEY Patented Nov. 1 2,v 1935 uNrrEo STATES GASEOUS ELECTRICDISCHARGE LAMP DEVICE Otto Iritae, Berlin, and Alfred Biittenauer,Berlin-Halensee Germany, vassignoril to General Electric Company, acorporation of New York Application February 5, 1034, Serial no. 709392In Germany February 22, 1933 4 Claims.

The present invention relates to gaseous electric discharge lamp devicesgenerally and more particularly the invention relates to such deviceshaving a gaseous atmosphere consisting oi, or comprising, a metal vapor.

Electric discharge lamp devices having a gaseous filling consisting oi,or comprising a metal vapor, such as cadmium, magnesium, or sodiumvapor, require a container consisting, at least in part, oi a glassresistant to the chemical efiects of such metal vapor. Such resistantglass is frequently unsuitable for sealing the current leads into saidcontainer and a glass, such as lead glass, which is non-resistant to themetal vapor in the container but which has better sealing qualities thanthe resistant glass, is used for sealing purposes in the stem parts ofthe container. The non-resistant glass stems must be protected from themetal vapor, and a wall of vapor resistant material interposed betweenthe electrodes and the stem and closing ofl the nonresistant stem partsoi the container from the other parts of the container is efiective forthis purpose. Another manner of protecting the non-resistant glass stemsis by precipitating thereon a coating of material resistant to thegaseous atmosphere.

The object oi the present invention is to provide in a gaseous electricdischarge device having a container the stem parts of which are subjectto attack by the vapor in the gaseous filling, a simple, effective andeasily mounted means to protect such non-resistant stem parts of thecontainer from the vapor. Further objects and advantages attaching tothe device and to its use and operation will be apparent to thoseskilled in the art from the following particular description.

In accordance with these objects the invention comprises a shield ofmaterial resistant to the chemical effects of the vapor in the gaseousfilling enclosing the non-resistant glass stems oi the container of thelamp device. When the stem part consists of a glass having a differentcoeillcient of expansion than the other glass parts of said container 2,graded-joint is necessary at the junction point of the stem part andsaid other parts. As parts of the graded-joint are subject to attack bythe vapor the shield also encloses the graded-joint. The shield is madeof a material chemically resistant to the gaseous atmos phere. The stempart and the graded joint of the container are thus completely protectedfrom chemical attack by the vapor during the operation of the lampdevice by a simple, easily mounted means.

In the drawing accompanying and forming part of this specification anembodiment oi the invention is shown, in which Fig. 1 is a sectionalview 01' one end 01 a gaseous electric discharge lamp device having thenew and novel stern protecting structure, and

Fig. 2 is a side elevational view of a complete gaseous electricdischarge lamp device embodying the present invention.

Like numbers denote like parts in both the figures.

Referring to Figures 1 and 2 of the drawing the gaseous electricdischarge lamp device comprises a tubular container I having a gaseousatmosphere therein comprising a gas, such as neon, and a vaporizablematerial, such as sodium. Said container I consists of a glass resistantto the chemical effects of the sodium va- 20 per, such as theboro-silicate glass disclosed in co-pending application Serial Number470,436, filed July 24, 1930, the inventors being Georg Gaidies andMarcello Pirani. A short, flared tube 2 of the same glass as saidcontainer I is fused 25 to said container I, as illustrated in Fig. 1 ofthe drawing. A stem tube 4 consisting oi a glass subject to attack bysodium vapor but having better sealing qualities than said resistantglass, such as lead glass, is joined to said tube 2 by the 30graded-joint 3. The structure of graded-joints for gaseous electricdischarge devices is well known in the art and such seals consist ofsections of materials fused together; the coemcient of expansion of eachsection is about interme- 35 diate that of the other sections contiguousthereto. A plurality of current leads are sealed into the pinch part 6of said stem tube 4. Said current leads consist of an external part I, apart 8 sealed into the pinch part 8 and a part 9 inside 40 saidcontainer I. The interior parts 9 of said current leads support anelectrode or electrodes mounted thereon, as shown in Figure 2. The part9 of each of the leads extending from the pinch part 6 of said stem 4into the container I is sur- 45 rounded by a close fitting tube I0 ofinsulating material, such as a tube of magnesium oxide, or aluminiumoxide. A shield in the form of a cap II of material resistant to thegaseous filling, such as chrom-iron, or a resistant glass, or insulationmaterial, fits over the stem 4 and rests aga nst thecircularprotuberance It in the flared tube 2 making a mechanical jointtherewith. The tubes I0 fit snugly into the openings in th cap II and acementing material, indicated I2,

such as a mixture of talc and water glass, is laid around the contiguousparts of said tubes I0 and the cap II to insure the closing of theopenings in said cap II. This cementing material is likewise placedaround the contiguous parts of the pinch part 6 of the stem 4 and theends of tubes i 0 to seal the joint therebetween, indicated at I4. Themetal vapor is thus prevented from penetrating into the interior of capII and from attacking said stem 4 or the step-seal I. An exhaust tube 5is fused to said stem 4 and said exhaust tube 5 communicates with theinterior of said container I through the mechanical joint between saidcap I I and the part ii of the tube 2, which joint is pervious to gasbut impervious to the vapor in said device. The container I is exhaustedthrough said tube I during the manufacturlng of the lamp device.

In Fig. 2 of the drawing we have illustrated a complete gaseous electriclamp discharge device having the stem parts thereof protected by thesimple, effective, easily mounted means of the present invention. Saidlamp device is of the positive column type and has thermionic electrodes 20 and 2| sealed therein at each end thereof. Said electrodes 20and II consist of a bar of electron emitting material, such as a bar ofbarium oxide, and a heating element, such as a tungsten wire wrappedaround said bar. It will be understood, of course that other types ofthermionic electrodes well known in the art are used when desired.

The stem structure illustrated in Fig. 1 has four electrode leads 9sealed into the stem 4 instead of two leads as illustrated in Fig. 2.This four lead stem structure is desirable when the tubular containerhas a stem at only one end thereof rather than a stem at each end of thecontainer as in Fig. 2. In the single stem structure of the containertwo of the electrode leads 9 and the insulation tubes III covering saidleads 9 extend along the container and terminate adjacent the end of thecontainer opposite that end whereat the stem 4 is mounted. An electrode,or electrodes is mounted on the elongated leads 9 and on the shorterleads I. This stem structure is also useful in connection with lampdevices having bulb shaped containers and a single stem.

In the above description and in the drawing we have described andillustrated the joint between the circular protuberance II and the capII as a mechanical joint and as being pervious to gas but impervious tosodium vapor so that the container I can be successfully exhaustedthrough the exhaust tube 5 opening into the interior of cap II. When itis desired to speed up the exhausting step in the manufacture of thelamp device another exhaust tube, indicated at 25 in Fig. 2, openingdirectly into the container I is provided in addition to the exhausttube 5. When desired, the cementing material indicated at I2 and I4 islaid around the joint between said cap I I and the part I3 of tube 3 tomake said joint substantially gas tight. In this case, of course, it isnecessary to provide an exhaust tube connecting with the interior ofcontainer I in addition to the exhaust tube 5, as shown at 25 of Fig. 2.

The above described lamp device starts as a gas lamp and operates as avapor lamp after the heat of the gas discharge has vaporized thevaporizable material in the container. A heat conservator enclosing thelamp device, such as a double walled jacket having thespace between thewalls evacuated. is usually provided in order to maintain an eiiectivevapor pressure in said container I during the operation of the device.

While we have shown and described and have pointed out in the annexedclaims certain novel features of the invention, it will be understood 5that various omissions, substitutions and changes in the forms anddetails of the device illustrated and in its use and operation may bemade by those skilled in the art without departing from the broad spiritand scope of the invention, for 10 example, the container i can consistof a nonresistant glass having a coating of resistant glass on theinterior thereof.

What we claim as new and desire to secure by Letters Patent of theUnited States is: 15 1. A gaseous electric discharge device comprising acontainer having an electrode supporting stem, electrodes and electrodeleads sealed therein, a gaseous atmosphere in said container, saidcontainer comprising a material inert with re- 20 spect to said gaseousatmosphere, the part of said stem into which said electrode leads aresealed being of a material subject to attack by said gaseous atmosphereand a tubular shield of material inert with respect to the gaseousatmosphere mounted on said stem, said tubular shield being closed at oneend and being greater in diameter and in length than the part of saidstem subject to attack by said gaseous atmosphere, the end of saidshield opposite the closed end thereof so being contiguous to and ofsmaller diameter than the part of said stem inert with respect to saidgaseous atmosphere.

2. A gaseous electric discharge device comprising a container having anelectrode supporting stem, a gaseous atmosphere therein comprising ametal vapor, an exhaust tube fused to said stem, electrode leads sealedinto said stem, electrodes mounted on said leads, said container beingof a glass inert with respect to said metal, the part 40 of said steminto which said electrode leads are sealed being of a material subjectto attack by said gaseous atmosphere and a tubular shield of materialinert with respect to the gaseous atmosphere mounted on said stem, saidtubular 45 shield being closed at one end and being greater in diameterand in length than the part of said stem subject to attack by saidgaseous atmosphere, the end of said shield opposite the closed endthereof being contiguous to and of smaller 50 diameter than the part ofsaid stem inert with respect to said gaseous atmosphere the jointbetween said shield and said stem being pervious to gas but imperviousto said metal vapor.

3. A stem structure for a gaseous electric discharge device having asealed container and a gaseous atmosphere therein, said stem comprisinga tube of glass subject to attack by the gaseous atmosphere in saiddevice, a tube of a glass inert with respect to the gaseous atmospherein the device and having a coeiilcient of expansion different from thatof said first mentioned tube, a graded-joint joining said tubes,electrode leads fused into said first mentioned tube, and a tubularshield of material inert with respect to said gaseous atmosphere mountedon said stem, said tubular shield being closed at one end and beinggreater in diameter and in length than the part of said stem subject toattack by said gaseous atmosphere, the end of said shield opposite theclosed 7 end thereof being contiguous to and of smaller diameter thanthe part of said stem inert with respect to said gaseous atmosphere.

4. A gaseous electric discharge device comprising a container having anelectrode supporting 78 l shield being closed at one end and beinggreater in diameter and in length than the part 0! said stem subject toattack by said gaseous atmosphere, the end 0! said shield opposite theclosed end thereof being contiguous to and of smaller diameter than thepart of said stem inert with respect to said gaseous atmosphere, thejoint between said shield and said stem being pervious to gas butimpervious to said metal vapor.

ALFRED RU'II'ENAUER. 1.

